Cement.



the cemented surfaces,

UNITED STATES PATENT OFFICE.

GEORGE S. JOHNSTON, OF CHICAGO,

COMPANY, OF CHICAGO, ILLINOIS,

ILLINOIS, ASSIGNOR T0 GEO. S. JOHNSTON A CORPORATION OF ILLINOIS.

Patented Mar. 23, 1915.

CEMENT.

1,132,721. Specification of Letters Patent. 30 Drawing. Application filed January 23, 1914. Serial No. 813,860.

To all whom it may concern:

Be it known that I, Gnonon S. JonNsToN, a citizen of. the United States, and a resi dent of Chicago, in the county of Cook and State of Illintis, have invented a certain new and useful Cement, of which the following is a specification.

My present invention has special referonce to the provision of a cement suitable for uniting spectacle or eyeglass lenses to their mountings, I

The difiiculty of uniting certain surfaces by means of cement is generally known, and among the most dillicult of such surfaces to so unit, are glass and the metals of which spectacle and eye glass mountings are usually made. While cements may be made to adhere to both glass and a metal, such adhesion as may be secured is destroyed in the course of time by the variation between the expansion and contraction of the glass and metal and of the cement following and occasioned by changes in temperature, or the adhesion may be destroyed by the shock re;- sulting'from'a blow or a fall a otherwise.

So faras 1 am aware, there no cement which'ivill unite glass and a metal, or more particularly spectacle and eye glass lenses with their mountings in a dependable and satisfactory manner.

I haveconcluded that if the initialrelative movement between the layerof eeihent and the suri'ace'to wliicliit isapplied, such as is caused by theeiipansion and'contraction or a shock, as above instanced, could be prevented,'a cen'ienting action could bese cured which would be dependable and satisfactory.

l have, I believe, accomplished the above object of preventing the 'ia slip between and have secured a dependable and satisfactory cement for glass and metal, and particularly for securing spectacle and eye glass lenses to their mountings, by means of the compound hereinafter described and claimed.

For cementing glass to a metal the coeilicient of expansion of a cement composed entirely of a cementitious element or elements is quite diil'erent from that of either of the cemented members, and

changes of temperature will cause tension or strain between the current and the in the lateral and vertical 'dant, or mhers.

cemented member. of this tension or strain is manifest chiefly direction. In. the lateral direction there is a tendency of thecement to move or slip upon the sur- The loosening effect '55 face of the cemented member which results in a gradual loosening of the cement beginning at the outer pcrtion of the cemented area. In the vertical direction this tension or. strain is manifestloy the linear difierence of expansion or contraction of the cement at dillcrent portions of the cemented area because of the variation in the thickness of the film or layer of cement. For eliminating this strain 1 have devised a cement composed of cementitious and non-cementitious elements. For the cementitious element 1 use mastic, copal, (laminar, shellac or some similar adhesive material with Which I thoroughly mix or incorporate certain non-cementitious elements such as glass, garnet, emery, quartz, silezi, calcium carbonate, barium sulfate, or rthcr suitable noncementi Linus substance the linear coel'licient of ex .pansion' f xvi more nearly that of eitl'ier of the c ito-Jl members than tl'iat of the 131 ll(59211 ?!illtlfillfs element or elements. For one or nure. oi the non-cementiticus elements of in csru-nt I make use of an abraitr-ria l of sufiicient hardness to alu'ade-ir indent the surface of either of the cemented numbers, such as glass, emery or "garnet. 'ihrs abradant element is in the form oi small grains or granules a portion of which lie in intimate contact with cemented members and which, by their alu'adaut"properties, tend to indent them selves intwthe surface of the cemented mean-i This indentation thus offers a mechanical resistance to the lateral movement or slip of the cement upon the cemented surfaces. already described. In addition to the abradant element I also incorporate in my cement other non'cementitious elements such as silcx. glass, garnet, emery, barium sulfate, quartz, or calcium carbonate in a nu re finely divided state than the abradant porti n. This finely divided portion may be abradant or non-abradant and is for the purpose of rendering the linear coefficient of expansion of the cement as a whole more nearly that of the cemented members than that of the ccmentitious element alone. By

the

i that, by the incorporation of the non-cem entitious elements described, the cementitious element is divided into numerous comparatively small areas of contact over the cemented areaby the interposition of the non-cementitious elements.

It will readily be seen that a more secure adhesion to the cemented member is thus secured for the reason that a variation of temperature suflicient to cause a loosening at the edge of the cemented area of a cement composed entirely of cementitious elements would be insullicient when the cemented area is divided into numerous small areas of contact.

' A desirable formula for compounding my cement is the following: Shellac, parts,-

1 glass grains, 25 parts, sllex, 5 partsfbariu'm sulfate, parts, calcium carbonatfZQ The proportions may be changedh's, cumstances may require, but whenthe d'e sired proportions have been' determi'id upon the various ingredients are bifo ugl 1 d gether and thoroughly mixed ore gled. The mass is then subjected to be until the cementitious portion "thereo fused with the other ingredients thoroug 33 mixed therein. The fused mass is mitted to harden, and it is then pulveri of the abradant and other cementitiously inert portions. It is then graded by aft The cement is finally a the powder upon the 'sur aces to be united,

subjecting the surfaces so owdered to heat until the cementitious e ement is fused and then putting the surfaces together and permitting the whole to cool, harden and solidify. It will then be found that the substantially in the .silex, barium sulfate,

1 azement for I ;e mountings, by crushing instead of grinding, which} tends to preserve the sharpness of the grains lenses have been firmly and dependably cemented in their mounts. 1 f

Having described my invention, what I claimas new and Patent, is

1. As a new article of manufacture, cement for joining eye glass crystals to theirmountings, comprising shellac, glass grains, silex, barium sulfate, and calcium carbonate, substantially in the proportions by weight of 40, 25, 5, 10 and res ectively. f

2. As a new article 0 manufacture, a cement for joining eye glass crystals to their mountings, comprising shellac, glass grains, silex, barium sulfate, and calcium carbonate, proportions by weight of shellac 40 parts,- glass grains and silex parts, and barium sulfate and calcium carbonate 30 parts. I

3. As a new article of manufacture, a

cement for joining'eye glass crystals to their mountings, comprising shellac, glass grams, the glass grains, silex, barium sulfate, and calcium carbonate together constituting at least 40 'per cent. by weight of the total eement.

."As a new article of manufacture, a cementffor joining eye glassicrystals to their mountings, Y comprising cementitious material, glass grains, silex, barium sulfate, and calcium carbonate, the cemejititious material constituting not over 60 per cent; by weight of the total cement.

5. As 'a new article of manufacture, a joiningeye glass crystals to their comprising cementitious material, glass rains, silex, barium sulfate, and calcium car onate, the cementitious material comprising substantially 40 per cent. by weight of the total, and the barium sulfate and calcium carbonate constituting substantially 30 per cent. by weight of the total.

In testimony whereof I aflix my signature inthe presence of two witnesses. 1

GEORGE S. JOHNSTON. Witnessesr C. C. ALLEN, BEN-I. T. Roonnonsn.

desire to secure by Letters and calcium carbonate, 

